The disclosure of the following priority application is herein incorporated by reference:
Japanese Patent Application No. 2000-16684 filed Jan. 26, 2000.
1. Field of the Invention
The present invention relates to a shield device which shields a gap between two members which relatively move with respect to one another, and more particularly relates to a shield device which intercepts light rays and prevent them from getting into the interior of an optical apparatus through a gap between the main body of the optical apparatus and a lens barrel comprised in the optical apparatus, and also relates to a camera.
2. Description of the Related Art
In the prior art, as a shield device which shields the gap between two members which move relative to one another (for example a main body and a cylindrical member), for example in Japanese Laid-Open Patent Publication No. H10-31146, it has been disclosed to provide a protuberance upon the sliding surface of the shield member which slides against the outer circumferential surface portion of the moving cylindrical member, and to increase the contact force of the shield member against the outer circumferential surface portion of the cylindrical member by the presence of this protuberance, so as to intercept the light rays. Further, in Japanese Laid-Open Patent Publications No. H8-146501 and No. H9-138334, it is disclosed to obtain increased shielding effectiveness by providing a plurality of protuberances upon the shield member which fit against the outer circumferential surface portion of a lens barrel.
However, if the movable cylindrical member is manufactured from a plastic material, depending upon the circumstances of the mold shape, a step or burr due to a parting line may be formed upon its outer circumferential surface. Even though this parting line step or burr typically is minute, it is unavoidable for it to cause a minute gap to be formed in the surface contact between the cylindrical member and the shield member. Furthermore, alternatively, if a minute particle of foreign matter should get caught between the cylindrical member and the shield member, this can also cause a minute gap of the same type to open up between them.
If a prior art type shield device is utilized with the intention of intercepting light from getting through the gap between the main body of the camera and the lens barrel, there has been the problem that light rays may get into the body of the camera through this minute gap and may expose the film, which is most undesirable.
The object of the present invention is to propose a shield device and a camera which can reliably and effectively intercept light rays, even if a minute gap is present in the fitting of the shield member upon the cylindrical member.
In order to attain the above object, a shield device according to the present invention comprises: a main body having an opening portion; a cylindrical member that is movable in a direction substantially perpendicular to the opening portion; and a shield member, an outer edge of which is engaged to an inner edge of the opening portion, and an inner edge of which is fitted upon an outer surface of the cylindrical member so as to be slidable thereon and so as to shield a gap between the main body and the cylindrical member, and: the cylindrical member is movable through the opening portion in a direction of a central axis of the cylindrical member; at least a portion of an outer circumferential surface of the cylindrical member has a shape different from another portion thereof along the direction of the central axis; and the shield member contacts along the outer circumferential surface having the different shape, as the cylindrical member moves in the direction of the central axis.
In this shield device, it is preferred that a diameter of the at least a portion of the cylindrical member is different from a diameter of the another portion of the cylindrical member. In this case, it is preferred that the at least a portion of the cylindrical member is an end portion of the cylindrical member. Furthermore, it is preferred that when the cylindrical member is retracted within the main body, the shield member contacts along a shape of the end portion of the cylindrical member.
Also, it is preferred that the shield member is ring shaped, and its inner peripheral portion is an elastic member which can contact along the outer circumferential surface having the different shape.
Also, it is preferred that at least a portion of a surface of the shield member contacting along the at least a portion of the outer circumferential surface having the different shape is not parallel to the central axis.
Also, it is preferred that a surface of the shield member contacting along the at least a portion of the outer circumferential surface having the different shape is bent in the direction of the central axis.
Also, it is preferred that: the cylindrical member has a groove provided in the outer circumferential surface, extending in a circumferential direction, as the different shape; and the shield member is ring shaped and has a protuberance, which roughly agrees in shape with the groove, upon a surface of an inner peripheral portion thereof which slides against the outer circumferential surface of the cylindrical member.
A camera according to the present invention, comprises: a body cover having an opening; a lens barrel which is movable in a direction substantially perpendicular to the opening of the cover; and a shield member, an outer edge of which is engaged to an inner edge of the opening, and an inner edge of which is fitted upon an outer circumferential surface of the lens barrel so as to be slidable thereon and so as to shield a gap between the body cover and the lens barrel, and: the lens barrel is movable through the opening along a direction of the optical axis of the lens barrel; the outer circumferential portion of the lens barrel has a ring shaped portion which is discontinuous in the direction of the optical axis of the lens barrel, at least at one place; and when the lens barrel is shifted to a predetermined position in the direction of the optical axis, the inner edge of the shield member contacts along the ring shaped portion which is discontinuous.